This invention relates to the field of guidewires or wire guides used for diagnostic, interventional, or therapeutic medical procedures which define and are carried out within a sterile field. More specifically, this invention relates to guidewires which are conveniently useable within the spatial limits of a sterile field. Guidewires of this invention also significantly reduce the likelihood that they will become contaminated by physical displacement from the sterile field or inadvertent contact with a non-sterile surface.
Guidewires are used in various medical procedures to gain vascular or non-vascular access to anatomical locations. The guidewire is initially introduced into the anatomy of a patient by means of a needle or other access device which in many procedures pierces the patient's skin. The guidewire is then advanced to a chosen or targeted anatomical location to provide a means of tracking guidance and support for other diagnostic, interventional, or therapeutic medical devices having lumens which can follow or track over a guidewire. Once such other medical devices reach their desired anatomical location, the guidewire is or can be withdrawn. The physician then proceeds with the protocol of the procedure. A specific but non-limiting example of the above is the placement of a multi-lumen catheter into the internal jugular vein for intraveneous delivery of medications. The physician achieves venous access with a percutaneous introducer needle which penetrates the surrounding tissue and vessel wall as it enters the vessel lumen. The guidewire is inserted through the introducer needle and advanced to the internal jugular vein. The needle is withdrawn over the guidewire and placed on the sterile field, i.e., the sterile area surrounding and adjacent to the site of the medical procedure. A dilating sheath is inserted over the guidewire and advanced through the skin to enlarge the percutaneous opening. The dilating sheath is withdrawn over the guidewire and placed in the sterile field. The multi-lumen catheter is then slid over the guidewire by means of one of its lumens and advanced to the desired location. Once the catheter reaches the desired position within the vessel, the guidewire is withdrawn and placed on the sterile field for possible future use.
Depending upon the nature and complexity of the procedure, the physician may need or may choose to reinsert or use a number of additional other diagnostic, interventional, or therapeutic devices during the procedure. For example, fluoroscopic imaging may disclose the catheter to be incorrectly positioned. In that instance, the physician may choose to reinsert the guidewire to provide support to the catheter as the catheter is withdrawn or advanced to the correct position. Reinsertion of such other medical devices will necessitate reinsertion of the guidewire into the vasculature or to some other desired anatomical site. Numerous other medical procedures requiring guidewire reinsertion will be known to one skilled in this art. Thus, the guidewire must be readily available for use and must maintain its sterility throughout what may be a lengthy procedure.
The devices utilized during a procedure (including the guidewire), are laid out on a sterile field to be readily accessible to the physician throughout the procedure. The sterile field may include a tray, a draped table, or a draped portion of the patient's body. Therefore, the sterile field may be limited in space and sometimes may not be level, but rather, uneven or tilted. For example, as a preventative measure for reducing the likelihood of introducing an air embolism during a central venous access procedure, the patient table is commonly tilted with the patient's head angled downward toward the floor.
As presently commercially available, a guidewire's unpackaged shape is similar to a linear spring ranging in length from 30 centimeters to 300 centimeters or more. The guidewire is usually packaged in a circular carrier known as a dispenser, which has been discussed in numerous United States patents including U.S. Pat. Nos. 5,443,081 and 5,279,573 both issued to James J. Klosterman. Once removed from the dispenser, the guidewire returns to its straight, substantially linear form. Because of the linear form and circular cross section of the guidewire, it may inadvertently become displaced from the sterile field by rolling or falling off. Additionally, its tendency to be linear may result in contact with a non-sterile surface outside of the limited sterile field such as a portion of the patient's body, or a portion of the physician's body or a contaminated object. In those instances where the guidewire is displaced from the sterile field and has become contaminated, it is necessary for the guidewire to be replaced with a second, sterile guidewire. Replacement of the guidewire because of loss of sterility is disruptive, inefficiently time consuming, and increases the cost of the procedure.
At least two approaches have been taken to reduce the likelihood that a guidewire will become contaminated by inadvertent contact or displacement from the sterile field. One approach is to reinsert the guidewire into its sterile dispenser, mentioned above, as it is partially or wholly withdrawn from the patient. While this approach is effective in protecting the wire from contamination, re-loading the guidewire into the dispenser and removing it therefrom for reuse requires additional time and may not be practical during a medical procedure.
A second approach of which the assignee of this application has become aware is to manufacture the guidewire from a material having a temperature dependent configuration , i.e., the configuration the guidewire tends to assume, is determined by the temperature to which the guidewire is exposed. Materials useable in this approach can be processed to have a tendency to coil at room temperature (e.g., 25.degree. C.) outside the body and to uncoil, i.e., to become substantially linear, at body temperature (e.g., 37.degree. C.) e.g., when it is reinserted into the body. As is well known in the medical device art, specific nickel titanium alloys (e.g., nitinol) can be processed to exhibit this behavior. This second approach has the significant drawback that the materials which are suitable for manufacturing guidewires and which exhibit a temperature dependent configuration are generally difficult to fabricate into conventional guidewires because they are resistant to conventional welding and brazing processes. Additionally, such temperature dependent materials tend to be more expensive than conventional metals such as medical grade stainless steel.
The present invention provides the physician with a means of efficiently, conveniently and cost effectively reducing the risk of inadvertent contamination of the guidewire during a medical procedure use and handling, without re-loading the guidewire into its dispenser or utilization of materials which exhibit temperature-dependent memory.